Field of the Invention
The invention relates to a method for adjusting cylinders in a printing machine, and to a printing machine suitable for performing the method.
Modern in-line sheet-fed offset rotary printing machines include a plurality of offset printing units and often a varnishing or lacquering unit downline from the offset printing units, and are thus set up as effectively as possible for the widest possible variety of printing jobs. Many of the printing jobs, although indeed requiring print carrier sheets to be printed in the printing units, do not need any varnishing of the sheets in the varnishing unit. The applicator cylinder of the varnishing unit is therefore thrown off from the impression cylinder for the printing jobs. In this adjustment of the applicator cylinder from a print-on position into a print-off position, a printing nip formed by the cylinders is opened slightly. When the sheets are being transported through this slightly opened printing nip, there is a risk that the sheets transported past the applicator cylinder on the impression cylinder will engage or impact the applicator cylinder, with the result that fresh ink applied to the sheets in the printing units becomes smeared onto the applicator cylinder.
It is therefore desirable for the printing nip between the impression cylinder and the applicator cylinder to be capable of being enlarged to such an extent that there is no longer any risk of the sheets impacting the applicator cylinder. This desire is often obstructed, however, by the fact that various components are arranged in the immediate vicinity of the applicator cylinder, such as, for example, the impression cylinder, a supply roller for supplying ink or varnish to the applicator cylinder, a blower for guiding the sheets, a washer for cleaning the applicator cylinder and a varnish bath or tub for storing the varnish printed by the applicator cylinder, and impede wide-ranging displacements of the applicator cylinder. Consequently, as a rule, it is possible for the applicator cylinder to be displaced out of the print-on position thereof into the print-off position thereof only over a short distance, with the result that the clearance between the applicator cylinder and the impression cylinder is not large enough.
In order to overcome this problem and prevent the sheets from impacting the inactive applicator cylinder, various possibilities are conceivable, some of which are explained briefly hereinbelow.
A first possibility would involve a simultaneous midpoint displacement of the applicator cylinder and the supply roller away from the impression cylinder, so that the printing nip is enlarged to a sufficient extent. However, a relatively complex adjustment mounting would be necessary for coupling the applicator cylinder to the supply roller in order to maintain permanent bearing contact of the applicator cylinder with the supply roller during the simultaneous displacement.
A second possibility would involve withdrawing away from the applicator cylinder, those components, such as the varnish bath or tub, the washer, and the blower, for example, which block the sufficiently wide displacement of the applicator cylinder, so that the applicator cylinder can be pivoted coaxially to the supply roller, in a direction of rotation corresponding to the direction of rotation of the impression cylinder during the transport of the sheets, into the free space resulting from the withdrawal. However, not every printing machine has sufficient free space for the withdrawal of the aforementioned components, and the bearing supports necessary for withdrawing the components are relatively costly.
A third possibility would be to remove the applicator cylinder not required for the current in-line process from the varnishing unit, so that the print carrier printed in the offset printing units can run through the varnishing unit without difficulty. However, a selective operation of the printing machine without the applicator cylinder presupposes specific constructive conditions. So that, with the applicator cylinder removed from the printing machine, the gearwheel arranged coaxially with the applicator cylinder for rotatively driving the latter can remain integrated as an intermediate wheel in a gear train of the printing machine, it is necessary to have a coupling for decoupling the applicator cylinder from the gearwheel remaining in the printing machine, and for coupling the applicator cylinder to the gearwheel when the latter is subsequently reinserted into the printing machine. For example, the coupling for separating and connecting an axle journal or kingpin could be arranged on this axle journal at the drive-side end of the applicator cylinder. After the separation of the axle journal, a journal part thereof, together with the gearwheel seated on this journal part and with a roller bearing for rotating the applicator cylinder, the journal part being inserted into the roller bearing, remains in the printing machine, while the applicator cylinder, together with the other journal part, can be removed from the printing machine. A coupling half of the coupling is located on each of the two journal parts. In order mutually to couple and decouple two journal parts of an applicator-cylinder axle journal arranged at the operating-side end of the applicator cylinder, a further coupling would be necessary. Thus, with the applicator cylinder removed, a journal part of the operating-side axle journal, together with an operating-side roller bearing of the applicator cylinder, could also remain in the printing machine.
It would therefore be necessary for the axle journals of the applicator cylinder to have a coupling constructed in a manner similar to that of the axle journals of a numbering shaft described in the published German Patent Document DE 34 07 681 C2. The coupling thereof is formed of a halfshell, a clamping jaw and a clamping screw/bayonet lock and is illustrated in FIG. 4 of this reference.
Although the construction outlay resulting from the coupling for the applicator cylinder would possibly yet be justifiable, it would be necessary, because of the great weight of the applicator cylinder, to have, in order to remove it, a pivoting device which would be constructed in accordance with the pivoting device identified by the reference numeral 20 in the just-mentioned published German patent document, and the construction thereof would therefore be too complicated.
In order to prevent the sheets transported past the applicator cylinder by the impression cylinder from impacting the applicator cylinder, there is, in addition to the three possibilities explained above, a fourth possibility which is described in the published German Patent Document DE 197 19 624 C1, which describes a method for adjusting a cylinder, wherein a cylinder gap of the applicator cylinder thrown off from the impression cylinder is oriented in a manner that the cylinder gap is directed towards the impression cylinder, with the result that an enlarged interspace is produced between the cylinders. Moreover, a sheet guide element is arranged in the cylinder gap, in order to press the sheets onto the impression cylinder. In order to integrate the sheet guide element into the cylinder gap, sufficient free space is required in the latter, which is generally not available, because blanket tensioners arranged in a cylinder gap take up a very large amount of construction space for themselves.
It is accordingly an object of the invention, therefore, to provide a method for adjusting a cylinder, by which an applicator cylinder can be adjusted in an uncomplicated manner to a sufficiently enlarged clearance relative to an impression cylinder, and to provide a printing machine by which the method can be performed, without requiring a sheet guiding element in the cylinder gap of the applicator cylinder.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method for adjusting a cylinder in a printing machine, which comprises, in a first step, rotating a first cylinder into a rotary position wherein a cylinder gap formed in the first cylinder is directed towards a second cylinder of the printing machine and, in a second step, displacing one of the two cylinders, with the second cylinder dipping into the cylinder gap.
In accordance with another mode, the method of the invention includes, in the second step, pivoting the second cylinder out of a first cylinder position located outside the cylinder gap, through the cylinder gap, and into a second cylinder position located outside the cylinder gap.
In accordance with a further mode of the method invention, in the second step, the pivoting of the second cylinder takes place coaxially with an axis of rotation of a supply roller.
In accordance with an added mode of the method invention, the first cylinder is an impression cylinder, and the second cylinder is an applicator cylinder.
In accordance with an additional mode, the method of the invention includes, in the second step, displacing the first cylinder in a direction towards the second cylinder.
In accordance with yet another mode of the method invention, the first cylinder is an applicator cylinder, and the second cylinder is a supply roller.
In accordance with another aspect of-the invention, there is provided a printing machine including an impression cylinder formed with a cylinder gap, and an applicator cylinder for applying ink or varnish onto a print carrier transported on the impression cylinder, comprising a bearing support whereon the applicator cylinder is mounted for displacing the applicator cylinder into the cylinder gap, and out of the cylinder gap again into a clearance position wherein it is disposed with a clearance relative to the impression cylinder.
In accordance with a further feature of the invention, the bearing support is formed as a pivot bearing for pivoting the applicator cylinder coaxially with a rotational axis of a supply roller for supplying ink or varnish to the applicator cylinder.
In accordance with an added feature of the invention, the bearing support is formed as a pivot bearing for pivoting the applicator cylinder about the pivot bearing into a clearance position in a rotational direction which, as viewed in the same viewing direction, is opposite to a rotational direction of the impression cylinder during the transport of the print carrier by the impression cylinder.
In accordance with an additional aspect of the invention, there is provided a printing machine including an applicator cylinder for applying ink or varnish to a print carrier and, a supply roller for supplying the ink or varnish to the applicator cylinder, comprising a first bearing support whereon the applicator cylinder is mounted for displacing the applicator cylinder in a direction towards the supply roller, and a second bearing support whereon the supply roller is mounted for holding the supply roller in a fixed position during the displacement of the applicator cylinder.
In accordance with yet another feature of the invention, the printing machine includes a securing device assigned to the applicator cylinder for retaining the applicator cylinder in a rotary position wherein a cylinder gap formed in the applicator cylinder is directed towards the supply roller.
In accordance with yet a further feature of the invention, the first bearing support is formed as a linear guide.
In accordance with yet an added aspect of the invention, there is provided a printing machine for performing a method of adjusting a cylinder therein, which includes, in a first step, rotating a first cylinder into a rotary position wherein a cylinder gap formed in the first cylinder is directed towards a second cylinder of the printing machine and, in a second o step, displacing one of the two cylinders, with the second cylinder dipping into the cylinder gap, the printing machine including an impression cylinder formed with a cylinder gap, and an applicator cylinder for applying ink or varnish onto a print carrier transported on the impression cylinder, and comprising a bearing support whereon the applicator cylinder is mounted for displacing the applicator cylinder into the cylinder gap, and out of the cylinder gap again into a clearance position wherein it is disposed with a clearance relative to the impression cylinder.
In accordance with a concomitant aspect of the invention, there is provided a printing machine for performing a method of adjusting a cylinder therein, which includes, in a first step, rotating a first cylinder into a rotary position wherein a cylinder gap formed in the first cylinder is directed towards a second cylinder of the printing machine and, in a second step, displacing one of the two cylinders, with the second cylinder dipping into the cylinder gap, the printing machine including an applicator cylinder for applying ink or varnish to a print carrier and, a supply roller for supplying the ink or varnish to the applicator cylinder, and comprising a first bearing support whereon the applicator cylinder is mounted for displacing the applicator cylinder in a direction towards the supply roller, and a second bearing support whereon the supply roller is mounted for holding the supply roller in a fixed position during the displacement of the applicator cylinder.
If, as aforementioned, a displacement of the first cylinder takes place in the second step, the cylinder gap formed in the first cylinder is slipped over the second cylinder which, without being itself displaced, can thus penetrate into the cylinder gap of the first cylinder. As a result of the displacement of the first cylinder, the latter can be adjusted out of the initial position thereof into a new position axially parallel to the initial position of the first cylinder.
If the displacement of the second cylinder takes place in the second step, the second cylinder is moved into the cylinder gap of the first cylinder, without requiring a displacement of the latter. As a result of the displacement of the second cylinder, the latter can be adjusted out of the initial position thereof into a new position axially parallel to the initial position of the second cylinder.
The first or the second cylinder displaced in the second step is preferably a printing-machine applicator cylinder which, as a result of the displacement thereof, is set at an enlarged circumferential surface clearance relative to an adjacent impression cylinder.
An advantage arising from the method according to the invention is that, at minimum outlay, a printing nip between the applicator cylinder and the impression cylinder can be set, so that, during the transport of a freshly printed or varnished print carrier sheet through the printing nip by the impression cylinder, there is no risk of the sheet impacting the applicator cylinder and consequently becoming smeared.
A first printing machine according to the invention, which is particularly advantageous for carrying out the method and is of uncomplicated construction, and which has an impression cylinder with a cylinder gap, and an applicator cylinder for applying ink or varnish to a print carrier transported onto the impression cylinder is distinguished by an applicator cylinder bearing support, by which the applicator cylinder can be displaced through the cylinder gap into a position with a clearance relative to the impression cylinder.
Thus, by the bearing support thereof, the applicator cylinder can be displaced in the following sequence out of an initial position into the cylinder gap, through the cylinder gap, out of the cylinder gap and into the clearance position and also in the opposite direction out of the clearance position into the cylinder gap, through the cylinder gap and back into the initial position. The printing machine is advantageous with regard to a gapless construction of the applicator cylinder. For example, a blanket sleeve or printing form sleeve for printing or varnishing may be slipped onto a cylinder core of the applicator cylinder. However, the first printing machine according to the invention is also advantageous with regard to a construction of the applicator cylinder with a cylinder gap which is built up with fittings, such as, for example, clamping and tensioning devices for holding a blanket or a printing or varnishing plate, which reach almost-as far as the circular-arcuate circumferential line (ideal in the region of the cylinder gap) of the applicator cylinder. Examples thereof are a fitting projecting out of the cylinder gap of the applicator cylinder or the sleeve of that part of the applicator cylinder which is moved through the cylinder gap of the impression cylinder during the displacement of the applicator cylinder.
A second printing machine according to the invention, which is likewise particularly advantageous for carrying out the method and is of uncomplicated construction, and which has an applicator cylinder for applying ink or varnish to a print carrier, and a supply roller for supplying ink or varnish to the applicator cylinder, is distinguished by a first bearing support and a second bearing support, the first bearing support being assigned to the applicator cylinder, in order to guide the applicator cylinder during the displacement thereof in a direction towards the supply roller, and the second bearing support being assigned to the supply roller, in order to retain the latter in a fixed position during the displacement of the applicator cylinder in a direction towards the supply roller.
The second printing machine is advantageous with regard to the cylinder gap of the impression cylinder being highly confined by fittings, such as, for example, tongs-type grippers and gripper supports for holding a print carrier sheet, where a movement of the, applicator cylinder through the cylinder gap is not possible, in contrast with the first printing machine. In the second printing machine, in a cylinder gap of the applicator cylinder, there can be sufficient free space for the penetration of the supply roller into the last-mentioned cylinder gap, between clamping and tensioning devices for holding a blanket or a printing or varnishing plate on the applicator cylinder. Thus, the supply roller of the second printing machine may have a gapless construction, as is customary.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as a method for adjusting a cylinder, and a printing machine for performing the method, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: